The absorption of thermal energy by a material having a positive thermal expansion coefficient causes the material to expand, which is an important consideration when manufacturing a device. For example, the changes that occur in the physical dimensions of circuit-board components upon heating can stress the board, thereby reducing its efficiency and lifetime. Many published documents refer to this problem. For instance, Williams etal. state that in "a magnetic field sensor . . . the temperature dependence of the Verdet constant and the thermal expansion of the material set a fundamental limit to the precision of the measurement." See "Compensation for Temperature Dependence of Faraday Effect in Diamagnetic Materials: Application to Optical Fibre Sensors," Electronics Letters, 27:1131-1132 (1991).
Electromechanical devices have been used to compensate for the changes that occur as a result of temperature-induced structural changes. For instance, in an electrical-mechanical positioner, a computer instructs a motor controller to move a motor shaft to induce corrections in the position of a movable object. The controller sends an electrical impulse that steps the motor shaft through electromagnetic induction. An encoder returns an electrical signal to the computer which determines the position of the movable object. The computer then decides whether another adjustment is necessary. Electrical-mechanical positioners require using these additional components to monitor and correct the position of the movable object. As a result, compensating for temperature-induced structural changes adds to the cost of manufacturing and the bulk of such devices.
Light transmission through an optical fiber heats the fiber through optical thermal absorption. For fibers having positive thermal expansion coefficients, this causes an increase in fiber length. This effect also has been considered a nuisance, primarily because the change in dimensions is associated with reduced performance for the apparatus in question.